How to fix last bone in armature?
Set up your bone chain with a spline IK, which is a different bone constraint than the standard IK. In Object Mode, create a path with Add &gt; Curve &gt; Path. Adjust it in Edit Mode to take the shape you want. Return to Object Mode and select your bone chain, then switch to Pose Mode. Go to the Bone Constraints Tab in the Properties Panel to create a Spline IK constraint. Give it the curve path you already created as its target. Provide the maximum number of bones to be effected, which presumably, is all of them in your case. After doing this, you can manipulate your bone chain by moving the control points of the path curve while in Edit Mode.
To keyframe changes to this rig, you will need a hook modifier. In Object Mode, create an empty and snap it at the outermost tip of your &quot;1 position&quot; bone. Select this empty, then hold  Shift, and select the Spline also, then go into Edit Mode, select the end point of the path which is closest to the &quot;1 position&quot; bone. Finally, press Ctrl + h to bring up the Hook menu. From the list, choose Hook to Selected Object. Now your rig will follow your empty, and you can keyframe the position of the empty in Object Mode.